Radiators with high aperture efficiency and low cross-polarization levels are desired aspects to achieve wide-band or multi-beam antenna design for modern telecommunications. It is desirable that the antenna size of such designs be compact and planar with respect to system integration, for example in antenna array structures. In the antenna array, there is a need to reduce antenna size and increase the antenna gain (e.g., in terms of efficient radiation of energy in the desired direction) to achieve the highest aperture efficiency for each antenna element in the array. In an antenna array, mutual coupling between the antenna elements typically diverts antenna power into unwanted side-lobe radiation patterns, which can reduce the gain of the antenna array.